1. Examination of the MHC restriction phenotype of thymocytes from thymusgrafted nude mice. 2. Examination of the MHC restriction phenotype of peripheral T lymphocytes from thymus-grafted nude mice. 3. Role of Epstein-Barr virus infection in the pathogenesis of chronic lymphocytic leukemia. 4. Gamma interferon production by antigen-specific T cell clones. 5. Analysis of the fine specificity of T cell antigen recognition and the influence of the MHC gene products on antigen recognition in T cell clones and T cell hybridomas. 6. Studies on the cell in the thymus responsible for the self-recognition specificity of maturing T cells.